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In this study, the in situ 4 wt.% TiB2(p)/Al-Cu composite was prepared through a mixed salt reaction method. To evaluate its formability, hot isothermal compression tests were performed using a Gleeble−3500 system in a temperature range of 480-510 °C and a strain rate range of 0.1-10 s−1. A constitutive model of the composites with strain compensation was established, and the true stress–strain curves revealed that the composite exhibited favorable formability at 510 °C. Additionally, single-pass equal channel angular pressing (ECAP) processes were conducted at room temperature and 510 °C to investigate the microstructure evolution of the composite. The distribution of TiB2 particles was found to be influenced by deformation temperature, while the microstructural characteristics of the aluminum matrix were minimally affected. Furthermore, a comparison between the as-cast composite and the deformed composites revealed the presence of different preferred orientations in the two conditions, and the corresponding paths of texture evolution were estimated accordingly. Remarkably, after undergoing single-pass ECAP, the Schmid factors of composites remained nearly unchanged, demonstrating that deformed composites were still appropriate for processing and as such demonstrating a potential route also for formability assessment.

This study is focused on how the application of pulsed substrate bias during cathodic arc deposition affects the microstructure, texture, grain size and phase composition of (Ti,Al)N coatings. A series of Tix-1AlxN, 0.25≤x≤0.55 coatings were deposited on WC-Co cemented carbide substrates with -30 V, -60 V and -300 V pulsing bias (duty cycle 10 % and a frequence of 1 kHz) under controlled chamber conditions at 4.5 Pa N2-gas and a substrate temperature about 400 °C. The pulsing parameters for the bias (voltage, duty cycle and frequency) were deliberately selected to influence structure, microstructure and composition of the deposited coatings. All Tix-1AlxN coatings had a consistent columnar cubic B1 structure regardless of their chemical composition. Coatings grown at -30 V and -60 V pulsed bias exhibited a pronounced <111> texture attributed to a kinetically driven mechanism influenced by the relative flux of ion species, affecting the surface migration of adatoms during growth. In contrast, the coatings grown with a pulsed bias of -300 V exhibited a reduced <111> texture and the onset of grains with <100> preferred orientation. The transition to the <100> orientation with increased ion energy agrees with the fact that the <111> directions expose the densest array of atoms to the ion beam during growth while the <100> are the most open channeling directions in a B1 structure. The correlation to the preferred with respect to pulsing conditions during growth, correlated to microstructure, grain size and phase composition be further discussed. Surface roughness was highest (Sa≈0.17-0.22 µm) for coating deposited at pulsed bias -30 V.

Polysilicon (poly-Si)-on-oxide passivating contact structures (POLO/TOPCon) enable high-efficiency solar cells as they simultaneously provide a very high level of surface passivation and a high conductance for either electrons or holes. The ease of incorporation with existing manufacturing lines and their tolerance for high-temperature processing has increased the wide acceptance of this structure in the PV industry. In this report, we explore the effects of short high-temperature annealing required for effective hydrogenation and formation of ohmic screen-printed contacts across a wide temperature range (636 °C–846 °C) on the stability of passivating contact structures. We study this on p-type c-Si substrates with phosphorus-doped (n-type) or boron-doped (p-type) polysilicon contacts capped with either an AlOx or SiNx coating. Our experimental results show that irrespective of the poly-Si doping type, AlOx-capped samples suffer a loss in surface passivation across the investigated temperature range, while SiNx-capped samples show an improvement at lower annealing temperatures. Above 744 °C, severely ruptured blisters occur for the samples coated with a SiNx layer, leading to lift-off of the poly layer in extreme cases, and in all cases, significant surface passivation losses, up to 99%. A study of the long-term stability of these fired samples under 1-sun illumination @ 140 °C shows that they suffer from both bulk and surface-like instabilities. Two degradation cycles were observed: the first, a boron-oxygen light-induced degradation (BO-LID) observed after 5 min, with capture cross-section ratios of 15.8–19.2, and a slower secondary degradation, similar to light and elevated temperature-induced degradation (LeTID), with maximum degradation reached after ∼ 14 days. The presence of a silicon nitride layer does not appear to influence the kinetics of post-degradation recovery. Our results suggest that the effect of firing may be influenced by the polarity of the bulk

The effect of the mutual doping of C, Si, and Al atoms on the electronic structure and magnetic properties of FeXO3 (X = C, Al, Si) compounds, which are constituent compounds of the Earth’s lower mantle, was studied. In our first principles calculations, it was found that doping with carbon for both FeSiO3 and FeAlO3 leads to the transition of the compound from a semi-metallic state to a metallic one. The values of the magnetic moments of Fe were obtained for pure and doped compounds. For the doped compounds, there is a tendency of the Fe magnetic moment to increase with the growth in the number of substituted ions in the case of replacing Si with C and Si for Al; on the contrary, in the case of replacing Al with C and Si, a decrease in the magnetic moment was revealed. For FeXO3 (X = C, Al, Si), the obtained magnetic moment values were found to be in a good agreement with the known experimental data. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

The experimental knowledge of the AlSb monolayer with double layer honeycomb structure is largely based on the recent publication (Le Qin et al 2021 ACS Nano 15 8184), where this monolayer was recently synthesized. Therefore, the aim of our research is to consequently explore the effects of substitutional doping and vacancy point defects on the electronic and magnetic properties of the novel hexagonal AlSb monolayer. Besides experimental reports, the phonon band structure and cohesive energy calculations confirm the stability of the AlSb monolayer. Its direct bandgap has been estimated to be 0.9 eV via the hybrid functional method, which is smaller than the value of 1.6 eV of bulk material. The majority of vacancy defects and substitutional dopants change the electronic properties of the AlSb monolayer from semiconducting to metallic. Moreover, the MgSb impurity has demonstrated the addition of ferromagnetic behavior to the material. It is revealed through the calculation of formation energy that in Al-rich conditions, the vacant site of VSb is the most stable, while in Sb-rich circumstances the point defect of VAl gets the title. The formation energy has also been calculated for the substitutional dopants, showing relative stability of the defected structures. We undertook this theoretical study to inspire many experimentalists to focus their efforts on AlSb monolayer growth incorporating different impurities. It has been shown here that defect engineering is a powerful tool to tune the properties of novel AlSb two-dimensional monolayer for advanced nanoelectronic applications. © 2021 IOP Publishing Ltd.

In this study, the corrosion behavior of the CuAl-NiC abradable seal coating system in chloride solution was investigated to systematically research the effect of porosity, multiphase, and multilayer structure on the corrosion failure. Through the composition and structure analysis, the corrosion process of the system was predicted and then verified with mercury intrusion porosimetry, cross-section SEM/EDS analysis, and electrochemical measurements. The results demonstrated that the interphase selective corrosion caused the porosity of the top layer to decrease first and then increase during the corrosion development. The interlayer galvanic corrosion, determined by the pore connectivity, is crucial for corrosion failure., QC 20220215

In situ Cu and S K-edge X-ray absorption spectroscopy (XAS) was used for the investigation of sulfur-poisoned and regenerated Cu-SSZ-13 selective catalytic reduction (SCR) catalysts. Highly dispersed sulfur in the oxidation state +6 was found in the catalysts. Even though a similar amount of sulfur was deposited in the catalysts poisoned at both 200 and 500 °C, a higher fraction of sulfur-free Cu species was seen for the catalyst poisoned at the higher temperature. Regeneration at 550 °C resulted in more sulfur-free Cu species in the catalyst poisoned at 500 °C, even though a higher amount of sulfur was detected in this catalyst compared to the regenerated catalyst poisoned at 200 °C. Inconsistencies between the amount of sulfur and the fraction of sulfur-free Cu species were attributed to the additional sulfur storage at sites that do not involve Cu. It was suggested that increased temperature of poisoning may facilitate the formation of Al sulfates along with Cu sulfates. These results provide the next step in detailed understanding of sulfur poisoning and regeneration of Cu-SSZ-13 catalysts., QC 20220517

In the present study, the hybrid reinforced magnetite; silicon carbide (Fe3O4-SiC) novel composite has been successfully fabricated by powder metallurgy method in the aluminum matrix. There is a demand in developing permanent magnetic composite with lightweight, corrosion resistance to develop the magnetic properties of aluminum matrix composites and obtain synchronization between electrical and thermal properties without mechanical degradation. Various researchers confirmed that Aluminum matrix composite (AMC) is an excellent multifunctional lightweight material with remarkable properties. However, to improve the wear resistance in the high-performance tribological application, hardness, and developing the corrosion resistance, magnetic, and thermal conductivity, optimized hybrid reinforcement of particulates magnetite, silicon carbide (SiC-Fe3O4) into an aluminum matrix needs to be examined. This study investigated the effect of adding 10, 15, 20, 30, 35 wt.% Fe3O4 and constant amount of 5 wt.% Mg saturate as a binder, and preparation and fabrication of hybrid metal matrix composite reinforced with constant amount of Fe3O4 (15, 30) wt. % and various silicon carbide particulates (10, 15, 20, 30) wt.% and 5 wt.% Mg as a binder. Commercially available pure aluminum powder, SiC, and Fe3O4 were used to fabricate through the powder metallurgy method. Mixed powders were mechanically milled for 2 h using a planetary ball mill, and compacted of blend powder at a load of 250 MPa, then sintered at a temperature of 600 °C. Field-emission scanning electron microscopy (FE-SEM), energy-dispersive x-ray (EDX), optical microscopy (OM), X-ray diffraction (XRD), VSM (Vibrating sample magnetometer) for magnetic properties, micro flash thermal conductivity, a four-probe system for measuring the electrical properties, mechanical properties (hardness, wear), potentiodynamic polarization measurements to investigate the corrosion behavior was used to evaluate hybrid reinforcements effects

In the present study, the hybrid reinforced magnetite; silicon carbide (Fe3O4-SiC) novel composite has been successfully fabricated by powder metallurgy method in the aluminum matrix. There is a demand in developing permanent magnetic composite with lightweight, corrosion resistance to develop the magnetic properties of aluminum matrix composites and obtain synchronization between electrical and thermal properties without mechanical degradation. Various researchers confirmed that Aluminum matrix composite (AMC) is an excellent multifunctional lightweight material with remarkable properties. However, to improve the wear resistance in the high-performance tribological application, hardness, and developing the corrosion resistance, magnetic, and thermal conductivity, optimized hybrid reinforcement of particulates magnetite, silicon carbide (SiC-Fe3O4) into an aluminum matrix needs to be examined. This study investigated the effect of adding 10, 15, 20, 30, 35 wt.% Fe3O4 and constant amount of 5 wt.% Mg saturate as a binder, and preparation and fabrication of hybrid metal matrix composite reinforced with constant amount of Fe3O4 (15, 30) wt. % and various silicon carbide particulates (10, 15, 20, 30) wt.% and 5 wt.% Mg as a binder. Commercially available pure aluminum powder, SiC, and Fe3O4 were used to fabricate through the powder metallurgy method. Mixed powders were mechanically milled for 2 h using a planetary ball mill, and compacted of blend powder at a load of 250 MPa, then sintered at a temperature of 600 °C. Field-emission scanning electron microscopy (FE-SEM), energy-dispersive x-ray (EDX), optical microscopy (OM), X-ray diffraction (XRD), VSM (Vibrating sample magnetometer) for magnetic properties, micro flash thermal conductivity, a four-probe system for measuring the electrical properties, mechanical properties (hardness, wear), potentiodynamic polarization measurements to investigate the corrosion behavior was used to evaluate hybrid reinforcements effects

Primary type polyhedral silicon crystals were observed in the vicinity of oxides located at or near the surface of strontium modified semi-solid Al–7Si–Mg castings. The coarse silicon polyhedrons were observed mainly on the outer side of oxides surrounding the macrosegregation regions. The silicon crystals most likely nucleated on AlP-particles located near the oxides. These AlP particles may nucleate on the wetted surface of oxides, or form at different locations in the interdendritic regions., Included in doctoral thesis in manuscript form.

Starting from a long aza-starphene neutral and nonmagnetic organic molecule, a single-molecule magnet is on-surface constructed using up to 3 light nonmagnetic aluminum (Al) atoms. Seldom observed in solution with transition-metal atoms and going from 1 to 3 Al coordinated atoms, the doublet-singlet-doublet transition is easily on-surface accessible using the scanning tunneling microscope single-atom and single-molecule manipulations on a gold(111) surface. With 3 coordinated Al atoms, the lateral vibration modes of the Al-3-aza-starphene molecule magnet are largely frozen. Using the Kondo states, this opens the observation of the in-phase Al vertical atom vibrations and out-of-phase central phenyl vibrations.

Channeling phenomena during ion implantation have been studied for 50 keV11B, 100 keV27Al and 240 keV71Ga in 4H-SiC by secondary ion mass spectrometry and medium energy ion backscattering. The same projected range is expected for the used energies while the channeling tails are shown to be substantially different, for example, channeled71Ga ions may travel 5 times as deep as11B. Ion implantation has been performed both at room temperature (RT) and at 400 °C, where channeling effects are reduced for the 400 °C implantation compared to that of the RT due to thermal vibrations of lattice atoms. The temperature effect is pronounced for71Ga but nearly negligible for11B at the used energies. The channeling phenomena are explained by three-dimensional Monte Carlo simulations. For standard implantations, i.e. 4° off the c-direction, it is found that a direction in-between the [000-1] and the [removed] crystal channels, results in deep channeling tails where the implanted ions follow the [000-1] and the [removed] directions., QC 20201130

This contribution deals with the numerical investigations to develop a novel process chain for hybrid solid components using Tailored Forming. For manufacturing a hybrid bearing bushing, co-extrusion is the first step to produce hybrid semi-finished workpieces followed by a die forging process, machining processes and hardening. Combining aluminium with steel, compounds with wear-resistant functional surfaces and reduced weight are realised. Numerical simulations are a decisive part of the process chain design, for example to determine suitable process parameters for the co-extrusion process and to predict the thickness of intermetallic phases in the joining zone using a macroscopic phenomenological model. A numerical design including a tool analysis of the die forging process was carried out taking the experimentally determined material properties and the temperature profile after inductive heating into account. Additionally, the damage and fatigue behaviour of the polycrystalline material of the joining zone are modelled at the microstructure level. Moreover, a new discretization scheme, namely the virtual element method, which is more efficient at grain level, is developed regarding a crystal plasticity framework. Numerical simulations are used to develop inductive heating strategies for the forming process and for the design of the inductive hardening of the functional surface at the end of the process chain. In order to investigate the performance of this hybrid machine element under application-oriented conditions, a contact simulation is linked with a statistical damage model to calculate the bearing fatigue. In this study, a general overview of the individual process steps is given and results of the respective models are presented. © 2020, The Author(s).

Celitement is a new type of cement that is based on hydraulic calcium-hydrosilicate (hCHS). It is produced by mechanochemical activation of Calcium-Silicate-Hydrates (C-S-H) in a grinding process. Due to the lack of typical clinker minerals, its CaO/SiO2 (C/S) ratio can be minimized from above 3 (as in Ordinary Portland Cement) down to 1, which significantly reduces the amount of CO2 released during processing. The reaction kinetics of hCHS differs from that of classical clinker phases due to the presence of highly reactive silicate species, which involve silanol groups instead of pure calcium silicates and aluminates and aluminoferrites. In contrast to Portland cement, no calcium hydroxide is formed during hydration, which otherwise regulates the Ca concentration. Without the buffering role of Ca(OH)2 the concentration of the dissolved species c(Ca2+) and c(SiO4 4−) and the corresponding pH must be controlled to ensure a reproducible reaction. Pure hCHS reacts isochemically with water, resulting in a C-S-H phase with the same chemical composition as a single hydration product, with a homogeneous distribution of the main elements Ca and Si throughout the sample. Here we study via nanoindentation tests, the mechanical properties of two different types of hardened pastes made out of Celitement (C/S = 1.28), with varying amounts of hCHS and variable water to cement ratio. We couple nanoindentation grids with Raman mappings to link the nanoscale mechanical properties to individual microstructural components, yielding in-depth insight into the mechanics of the mineralogical phases constituting the hardened cement paste. We show that we can identify in hardened Celitement paste both fresh C-S-H with varying density, and C-S-H from the raw material using their specific Raman spectra, while simultaneously measuring their mechanical properties. Albeit not suitable for phase identification, supplemental EDX measurements provide valuable information about the distribution of a

This contribution deals with the numerical investigations to develop a novel process chain for hybrid solid components using Tailored Forming. For manufacturing a hybrid bearing bushing, co-extrusion is the first step to produce hybrid semi-finished workpieces followed by a die forging process, machining processes and hardening. Combining aluminium with steel, compounds with wear-resistant functional surfaces and reduced weight are realised. Numerical simulations are a decisive part of the process chain design, for example to determine suitable process parameters for the co-extrusion process and to predict the thickness of intermetallic phases in the joining zone using a macroscopic phenomenological model. A numerical design including a tool analysis of the die forging process was carried out taking the experimentally determined material properties and the temperature profile after inductive heating into account. Additionally, the damage and fatigue behaviour of the polycrystalline material of the joining zone are modelled at the microstructure level. Moreover, a new discretization scheme, namely the virtual element method, which is more efficient at grain level, is developed regarding a crystal plasticity framework. Numerical simulations are used to develop inductive heating strategies for the forming process and for the design of the inductive hardening of the functional surface at the end of the process chain. In order to investigate the performance of this hybrid machine element under application-oriented conditions, a contact simulation is linked with a statistical damage model to calculate the bearing fatigue. In this study, a general overview of the individual process steps is given and results of the respective models are presented. © 2020, The Author(s).

Thermal stabilizers, lubricant, and plasticizers are three crucial additives for processing poly(vinyl chloride) (PVC). In this study, a new mannitol stearate ester-based aluminum alkoxide (MSE-Al) was designed and synthesized as a novel additive for PVC. The thermal stability and processing performance of PVC stabilized by MSE-Al were evaluated by the Congo red test, conductivity measurement, thermal aging test, ultravioletevisible (UV–Vis) spectroscopy test, and torque rheometer test. Results showed that the addition of MSE-Al could not only markedly improve the long-term thermal stability of PVC, but also greatly accelerate the plasticizing and decrease the balance torque, which demonstrated that MSE-Al possessed a lubricating property. Thus, MSE-Al was demonstrated to be able to provide tri-functional additive roles, e.g., thermal stabilizer, plasticizer, and lubricant. The test results for the thermal stability of PVC indicated that the initial whiteness of PVC stabilized by MSE-Al was not good enough, thus the synergistic effect of MSE-Al with zinc stearates (ZnSt2) on the thermal stability of PVC was also investigated. The results showed that there is an appreciable synergistic effect between MSE-Al and ZnSt2. The thermal stabilization mechanism and synergism effect of MSE-Al with ZnSt2 are then discussed.

NASICON-type conductors based on LiGe2(PO4)3 are very promising lithium-conducting electrolytes for all-solid-state lithium-ion and lithium batteries. Al-doped LiGe2(PO4)3 solid electrolytes possessed higher conductivity (∼10-4 S/cm at room temperature) and stability versus metallic Li. In this paper, we present the structure study of Li1.5Al0.5Ge1.5(PO4)3 compound. Fast lithium-ion conductor Li1.5Al0.5Ge1.5(PO4)3 solid electrolyte have been obtained through glass crystallization at 820 °C during 8 h. Structural positions occupied by atoms have been examined by solid state nuclear magnetic resonance experiments. 6Li, 7Li, 27Al 31P NMR measurements have been performed at room temperature. © Published under licence by IOP Publishing Ltd.

The mechanical properties and microstructure of as-cast and homogenized AA7075 were investigated. This alloy was modified by adding transition elements 0.3%Sc + 0.5%Zr, 1%Ti + 0.2%B, and 1%Fe + 1%Ni for use in additive manufacturing applications. After adding Ti + B and Sc + Zr, the structure became uniform and finer with the formation of the Al3(Sc, Zr) and TiB2 phases. Coarse structures were obtained with the formation of an extremely unfavorable morphology, close to a needle-like structure when Fe + Ni was added. The mechanical properties of the modified alloys were increased compared to those of the standard alloy, where the best ultimate tensile strength (UTS) and yield strength (YS) were obtained in the AA7075-TiB alloy compared to the standard alloy in as-cast and homogenized conditions, and the highest hardness value was provided by Fe + Ni additives. The effect of the laser melting process on the microstructure and mechanical properties was investigated. Single laser melts were performed on these alloys using 330 V and a scanning speed of 8 mm/s. During the laser melting, the liquation of the alloying elements occurred due to non-equilibrium solidification. A change in the microstructures was observed within the melt zone and heat-affected zone (HAZ). The hardness of the laser-melted zone (LMZ) after adding the modification elements was increased in comparison with that of the standard alloy. Corrosion testing was performed using a solution of 100 mL distilled water, 3.1 g NaCl, and 1 mL HCl over 5, 10, and 30 min and 1 and 2 h. The corrosion resistance of the alloy modified with FeNi was low because of the non-uniform elemental distribution along the LMZ, but in the case of modification with ScZr and TiB, the corrosion resistance was better compared to that of the standard alloy. © 2019 by the authors.

This paper presents the results of a systematic study of helium swelling and the subsequent process of degradation of the near-surface layer of aluminum-based nitride ceramics. The samples were irradiated with 40 keV He2+ ions at temperatures of 300 and 1000 K with a fluence of 1 × 1017-5 × 1017 ions/cm2. The choice of radiation doses and temperature conditions was due to the possibility of simulating reactor tests of structural materials. It has been established that an increase in the irradiation fluence leads to the formation of large agglomerates of clusters of helium bubbles, as well as an increase in the degree of roughness and waviness of the surface with the formation of crater-like inclusions. In the case of irradiation at high temperatures, there was a slight decrease in the average size of helium inclusions compared with irradiation at room temperature. However, the density of inclusions and surface roughness were much higher. It is established that irradiation at room temperatures leads to a sharp decrease in ceramics density, as well as deformation of the crystal structure due to an increase in the density of dislocations and macrostresses in the structure. The decrease in ceramics density due to the formation of helium inclusions led to an increase in porosity and a defective fraction in the structure of the surface layer of ceramics. © 2019 by the authors.

Thermal stabilizers, lubricant, and plasticizers are three crucial additives for processing poly(vinyl chloride) (PVC). In this study, a new mannitol stearate ester-based aluminum alkoxide (MSE-Al) was designed and synthesized as a novel additive for PVC. The thermal stability and processing performance of PVC stabilized by MSE-Al were evaluated by the Congo red test, conductivity measurement, thermal aging test, ultravioletevisible (UV–Vis) spectroscopy test, and torque rheometer test. Results showed that the addition of MSE-Al could not only markedly improve the long-term thermal stability of PVC, but also greatly accelerate the plasticizing and decrease the balance torque, which demonstrated that MSE-Al possessed a lubricating property. Thus, MSE-Al was demonstrated to be able to provide tri-functional additive roles, e.g., thermal stabilizer, plasticizer, and lubricant. The test results for the thermal stability of PVC indicated that the initial whiteness of PVC stabilized by MSE-Al was not good enough, thus the synergistic effect of MSE-Al with zinc stearates (ZnSt2) on the thermal stability of PVC was also investigated. The results showed that there is an appreciable synergistic effect between MSE-Al and ZnSt2. The thermal stabilization mechanism and synergism effect of MSE-Al with ZnSt2 are then discussed.

Thermo-mechanical deformation, thermal resistance, and lateral temperature distribution were experimentally studied for a high-power AlGaInN LED chip-on-board array at three different input powers. A fullscale CFD model of the LED assembly was developed and correlated with the temperature and average thermal resistance measurements to enable prediction of the temperature distribution on the surface of a thermally deformed LED assembly. Application of the thermal resistance partitioning approach to thermal modeling of the deformed LED assemblies was discussed. It can be useful for design engineers for estimation of the temperature distribution across the deformed LED array, at the minimum number of temperature measurements required for model calibration.

In this work we have experimentally studied the impact of bentonite clay on the process of radiation-induced copper corrosion in anoxic water. The motivation for this is to further develop our understanding of radiation-driven processes occurring in deep geological repositories for spent nuclear fuel where copper canisters containing the spent nuclear fuel will be embedded in compacted bentonite. Experiments on radiation-induced corrosion in the presence and absence of bentonite were performed along with experiments elucidating the impact irradiation on the Cu2+ adsorption capacity of bentonite. The experiments presented in this work show that the presence of bentonite clay has no or very little effect on the magnitude of radiation-induced corrosion of copper in anoxic aqueous systems. The absence of a protective effect similar to that observed for radiation-induced dissolution of UO2 is attributed to differences in the corrosion mechanism. This provides further support for the previously proposed mechanism where the hydroxyl radical is the key radiolytic oxidant responsible for the corrosion of copper. The radiation effect on the bentonite sorption capacity of Cu2+ (reduced capacity) is in line with what has previously been reported for other cations. The reduced cation sorption capacity is partly attributed to a loss of Al-OH sites upon irradiation., Export Date: 13 February 2018; Article; CODEN: RPCHD; Correspondence Address: Jonsson, M.; School of Chemical Science and Engineering, Applied Physical Chemistry, KTH Royal Institute of TechnologySweden; email: matsj@kth.se; Funding details: SKB, Svensk Kärnbränslehantering. QC 20180326

The possibility is demonstrated of adsorption extraction of vanadium compounds from acid media with modified aluminum silicate. Very fine layered aluminum silicate modified with surfactant cations (didecyldimethyl ammonium chloride) were used for extracting vanadium compounds. Sorbent modification proceeds as a result of fastening didecyldimethyl ammonium chloride molecules in the space between sorbent layers. As a result of modification, the sorbent acquires the property of selective absorption of vanadium compounds from solution. In order that the sorbent is not compacted and passes solution without hindrance, it is applied to quartz sand with a particle size of 1–3 mm treated with polyacrylamide. Vanadium compound adsorption proceeds most completely at pH 2.8–3.4, which is connected with the existence in the solution of various polyoxo compounds. The possibility is established of repeated sorbent use in adsorption and desorption cycles. The constant volume content of sorbent is 0.64 mmole/g, the dynamic exchange capacity is 0.38 mmole/g, and the static exchange capacity is 0.26 mmole/g. The solution after the desorption cycle is used for preparing pure vanadium pentoxide by hydrolytic precipitation under conditions of achieving the required concentration. Results of extracting vanadium compounds from model solutions correspond to vanadium adsorption on colloidal modified aluminum silicate from Chusovskoi Metallurgical Plant (ChMZ) washing solutions. © 2017, Springer Science+Business Media, LLC, part of Springer Nature.

Luminescent transparent nanoceramics were obtained by thermobaric treatment (TBT) of magnesium aluminium spinel nanopowder. The morphological features were studied by scanning electron microscopy combined with X-ray powder diffraction. Obtained ceramics do not have any agglomerates and pores larger than 100 nm. Crystallites have a high size uniformity. An increase in the lattice constant of nanoceramics compared to the initial powder is observed. Under the TBT, a decrease in the region of coherent scattering due to elastic deformation of crystallites is found. The absence of cracks, large pores, nanosize grains, and high size uniformity reduce light loss in the material, increasing its transparency. Point defects were characterized by photoluminescence and electron spin resonance (ESR) methods. The glow in the 1.8 eV band is caused by the presence of Ti3+ impurity ions. An abnormally wide peak with a maximum at 2.4 eV in the photoluminescence spectrum is recorded. This signal is a superposition of the Mn2+ ions emission bands and oxygen vacancies (F and F+ centres). In the ESR spectrum, signals from impurity ions of iron, titanium, and manganese, as well as an intense signal at g = 2.005 associated with oxygen vacancies in nanoceramics were detected. © 2018 Institute of Physics Publishing. All rights reserved.

Zinc oxide (ZnO) has a very broad and versatile range of applications provided by its high abundance and optical and electrical properties, which can be further tuned by donor substitution. Al-doped ZnO is probably the most thoroughly investigated material with regard to thermoelectric properties. Fairly reasonable electrical properties of donor-doped zinc oxide are usually combined with high thermal conductivity limiting potential applications. Here we report a new self-forming nanocomposite concept for ZnO-based thermoelectrics, where a controllable interplay between the exsolution of the nanophases and modification of the host matrix suppresses the thermal transport while imparting enhanced electrical performance. The thermoelectric performance of the best-obtained composite, described by the dimensionless figure-of-merit ZT, at 920-1200 K is almost twice that of the pure matrix composition and reaches up to 0.11. The proposed approach invokes controlled interactions between composite components as a novel tool for decoupling the electrical and thermal transport parameters and shows clear prospects for an implementation in other thermoelectric oxide systems. The results indicate that the proposed concept may also constitute a promising pathway to achieve stable electrical performance at high temperatures, which currently represents one of the major challenges towards achieving ZnO-based thermoelectrics. © The Royal Society of Chemistry.

The possibility is demonstrated of adsorption extraction of vanadium compounds from acid media with modified aluminum silicate. Very fine layered aluminum silicate modified with surfactant cations (didecyldimethyl ammonium chloride) were used for extracting vanadium compounds. Sorbent modification proceeds as a result of fastening didecyldimethyl ammonium chloride molecules in the space between sorbent layers. As a result of modification, the sorbent acquires the property of selective absorption of vanadium compounds from solution. In order that the sorbent is not compacted and passes solution without hindrance, it is applied to quartz sand with a particle size of 1–3 mm treated with polyacrylamide. Vanadium compound adsorption proceeds most completely at pH 2.8–3.4, which is connected with the existence in the solution of various polyoxo compounds. The possibility is established of repeated sorbent use in adsorption and desorption cycles. The constant volume content of sorbent is 0.64 mmole/g, the dynamic exchange capacity is 0.38 mmole/g, and the static exchange capacity is 0.26 mmole/g. The solution after the desorption cycle is used for preparing pure vanadium pentoxide by hydrolytic precipitation under conditions of achieving the required concentration. Results of extracting vanadium compounds from model solutions correspond to vanadium adsorption on colloidal modified aluminum silicate from Chusovskoi Metallurgical Plant (ChMZ) washing solutions. © 2017, Springer Science+Business Media, LLC, part of Springer Nature.

We examine two different silicon solar cell designs featuring full-area electron-selective contacts based on ultrathin (2-3 nm) titanium oxide (TiOx) films deposited by atomic layer deposition. The first cell design applies a layer stack to the cell front, which is composed of an ultrathin intrinsic amorphous silicon (i-a-Si:H) layer for interface passivation, the TiOx film and an indium tin oxide (ITO) layer to provide a good lateral conductance for electrons to the metal fingers. Whereas carrier lifetime measurements on test structures promise high implied open-circuit voltages Voc up to 726 mV, the realized solar cells achieve disappointingly low Voc values <400 mV. The J-V parameters of this cell type are negatively affected by a reverse diode occurring due to the contacting of the TiOx by the high-work function ITO layer. In the second cell type, we implement a layer stack to the cell rear, which is composed of an ultrathin silicon oxide (SiOy) layer, the TiOx film and a full-area-deposited aluminum (Al) layer. Initial Voc values of these cells are relatively low (<600 mV), but improve significantly after annealing at 350°C. The best cell featuring a SiOy/TiOx/Al rear contact achieves an open-circuit voltage of 661 mV and an efficiency of 20.3%. No reverse diode is observed, which is attributed to the lower work function of the Al compared to ITO in the first cell design. From internal quantum efficiency measurements, we extract a rear surface recombination velocity Srear of (52±20) cm/s for our best cell, which is well compatible with efficiencies exceeding 23%.

Sydvatten AB operates the water plant Ringsjö Agency in Stehag, Southern Sweden, and the company has since the 1970s deposited waterworks sludge in the sludge landfill at Rönneholms Mosse (bog), Sjöholmen (WGS84 55°48'46.1"N 13°18'25.6"E). In order to handle the produced future waterworks sludge from Ringsjö there was carried out a trenching and stratigraphic study of Ringsjö Agency waterworks sludge. The aim of the project was to roughly determine the mass balance for Fe and Al for the basis of the results to determine potential extraction and recycling opportunities for the iron and/or aluminum hydroxides of water treatment sludge. In addition trace elements and rare earth elements (REE) were studied. Analysis of 10 cores were characterized by technogenic stratigraphy, texture and color, results of geochemical studies of processed sludge recovered possible recycling opportunities to implement circular economy principles in sludge management. The Interreg Baltic Sea Region within the scope of project “Interactive Water Management” (IWAMA) has supported this study.

The Al-Si cast alloy family is widely used in the production of complex castings for various applications and known for its very good castability and high strength-to-weight ratio. However, early cracking under tensile loading is sometimes a limiting factor. Among other parameters, it is yet controversial whether grain boundaries are dominant strengthening factor in cast alloys, instead of dendrite/eutectic boundaries. This study presents the effect of secondary dendrite arm spacing (SDAS) and grain size on crack initiation and propagation of Al-Si cast alloys under tensile loading. The Al-10Si (wt.%) alloy with modified Si morphology was cast using inoculants (Al-5Ti-B master alloy) under different cooling rates to obtain a range of grain sizes (from below 138 μm to above 300 μm) and SDAS (6, 15 and 35 μm). Conventional tensile test as well as in-situ tensile test in a scanning electron microscope, equipped with an electron backscatter diffraction (EBSD) was carried out to understand the deformation mechanisms of the alloy. Observation of slip bands within the dendrites showed that in modified Si structure, the interdendritic (eutectic) area takes more portion of the strain during plastic deformation. Besides, only a few cracks were initiated at the grain boundaries; they were mostly initiated from dendrite/eutectic interface. All cracks propagated trans-granularly. Hall-Petch calculations also showed a strong relationship between SDAS and flow stress of the cast alloy. Although statistically correct, there was no physically meaningful relationship between the grain size and the flow stress. Nevertheless, formation of identical slip bands in each grain could be an evidence for the marginal effect of the grain size on the overall strength development of the alloy. Consequently, among other effects, the combinational dominant effect of SDAS and modest effect of grain size shall be considered for modification of the Hall-Petch equation for precise prediction of mechan

The Al-Si cast alloy family is widely used in the production of complex castings for various applications and known for its very good castability and high strength-to-weight ratio. However, early cracking under tensile loading is sometimes a limiting factor. Among other parameters, it is yet controversial whether grain boundaries are dominant strengthening factor in cast alloys, instead of dendrite/eutectic boundaries. This study presents the effect of secondary dendrite arm spacing (SDAS) and grain size on crack initiation and propagation of Al-Si cast alloys under tensile loading. The Al-10Si (wt.%) alloy with modified Si morphology was cast using inoculants (Al-5Ti-B master alloy) under different cooling rates to obtain a range of grain sizes (from below 138 μm to above 300 μm) and SDAS (6, 15 and 35 μm). Conventional tensile test as well as in-situ tensile test in a scanning electron microscope, equipped with an electron backscatter diffraction (EBSD) was carried out to understand the deformation mechanisms of the alloy. Observation of slip bands within the dendrites showed that in modified Si structure, the interdendritic (eutectic) area takes more portion of the strain during plastic deformation. Besides, only a few cracks were initiated at the grain boundaries; they were mostly initiated from dendrite/eutectic interface. All cracks propagated trans-granularly. Hall-Petch calculations also showed a strong relationship between SDAS and flow stress of the cast alloy. Although statistically correct, there was no physically meaningful relationship between the grain size and the flow stress. Nevertheless, formation of identical slip bands in each grain could be an evidence for the marginal effect of the grain size on the overall strength development of the alloy. Consequently, among other effects, the combinational dominant effect of SDAS and modest effect of grain size shall be considered for modification of the Hall-Petch equation for precise prediction of mechan

The Al-Si cast alloy family is widely used in the production of complex castings for various applications and known for its very good castability and high strength-to-weight ratio. However, early cracking under tensile loading is sometimes a limiting factor. Among other parameters, it is yet controversial whether grain boundaries are dominant strengthening factor in cast alloys, instead of dendrite/eutectic boundaries. This study presents the effect of secondary dendrite arm spacing (SDAS) and grain size on crack initiation and propagation of Al-Si cast alloys under tensile loading. The Al-10Si (wt.%) alloy with modified Si morphology was cast using inoculants (Al-5Ti-B master alloy) under different cooling rates to obtain a range of grain sizes (from below 138 μm to above 300 μm) and SDAS (6, 15 and 35 μm). Conventional tensile test as well as in-situ tensile test in a scanning electron microscope, equipped with an electron backscatter diffraction (EBSD) was carried out to understand the deformation mechanisms of the alloy. Observation of slip bands within the dendrites showed that in modified Si structure, the interdendritic (eutectic) area takes more portion of the strain during plastic deformation. Besides, only a few cracks were initiated at the grain boundaries; they were mostly initiated from dendrite/eutectic interface. All cracks propagated trans-granularly. Hall-Petch calculations also showed a strong relationship between SDAS and flow stress of the cast alloy. Although statistically correct, there was no physically meaningful relationship between the grain size and the flow stress. Nevertheless, formation of identical slip bands in each grain could be an evidence for the marginal effect of the grain size on the overall strength development of the alloy. Consequently, among other effects, the combinational dominant effect of SDAS and modest effect of grain size shall be considered for modification of the Hall-Petch equation for precise prediction of mechan

The Al-Si cast alloy family is widely used in the production of complex castings for various applications and known for its very good castability and high strength-to-weight ratio. However, early cracking under tensile loading is sometimes a limiting factor. Among other parameters, it is yet controversial whether grain boundaries are dominant strengthening factor in cast alloys, instead of dendrite/eutectic boundaries. This study presents the effect of secondary dendrite arm spacing (SDAS) and grain size on crack initiation and propagation of Al-Si cast alloys under tensile loading. The Al-10Si (wt.%) alloy with modified Si morphology was cast using inoculants (Al-5Ti-B master alloy) under different cooling rates to obtain a range of grain sizes (from below 138 μm to above 300 μm) and SDAS (6, 15 and 35 μm). Conventional tensile test as well as in-situ tensile test in a scanning electron microscope, equipped with an electron backscatter diffraction (EBSD) was carried out to understand the deformation mechanisms of the alloy. Observation of slip bands within the dendrites showed that in modified Si structure, the interdendritic (eutectic) area takes more portion of the strain during plastic deformation. Besides, only a few cracks were initiated at the grain boundaries; they were mostly initiated from dendrite/eutectic interface. All cracks propagated trans-granularly. Hall-Petch calculations also showed a strong relationship between SDAS and flow stress of the cast alloy. Although statistically correct, there was no physically meaningful relationship between the grain size and the flow stress. Nevertheless, formation of identical slip bands in each grain could be an evidence for the marginal effect of the grain size on the overall strength development of the alloy. Consequently, among other effects, the combinational dominant effect of SDAS and modest effect of grain size shall be considered for modification of the Hall-Petch equation for precise prediction of mechan

Paper reports the effect of a 10 keV, 110 keV and 10 MeV electron beam irradiation on optical and luminescence properties of LiBaAlF6 (LBAF) single crystals at 10, 90, and 293 K. Five absorption bands at 2.0, 3.2, 4.3, 4.9 and 5.5 eV were revealed in irradiated crystals in the energy range of 1.2–9.5 eV. Several PL emission bands (1.7–1.8, 2.2 and 2.5–3.5 eV) related to defects were found in the luminescence spectra at room temperature, while only one luminescence band at E = 2.2 eV appears at T = 90 K in LBAF crystals after a 10 MeV electron bombardment. The PL excitation spectra and time-response for these emission bands were studied at 10, 90, and 293 K. Thermoluminescence (TL) of irradiated crystals was studied in the temperature range of 90–740 K. New TL glow peaks at 166, 530 and 670 K were revealed and their parameters were determined. Temperature dependence of relative photoluminescence yield recorded monitoring emission at the 1.87 and 2.23 eV in the temperature range from 130 to 450 K, were fitted using five quenching processes related to TL glow peaks revealed in our research. Significant similarity in the manifestation of radiation-induced defects for LBAF and previously studied LiBaF3 single crystals is noted. The effect of an electron beam irradiation on optical and luminescence properties of LBAF single crystals and possible origin of the radiation defects were discussed. © 2017 Elsevier B.V.

Al-12Si specimens are produced by selective laser melting (SLM) from gas atomized powders. Installation for the production of powder is original. All specimens were prepared using the EOSINT M 280 device. A fine cellular structure is observed with residual free Si along the cellular boundaries. Room temperature tensile tests reveal remarkable mechanical behavior: the samples show yield and tensile strengths of about 102 MPa and 425 MPa, respectively, along with fracture strain of 12%. The study of crack surface morphology was shown by the example of a sample. Except the spherical pores, the interface of the molten pool also appears on the fracture surface, which indicates a mixture of fragile and ductile fracture. Additionally, the agglomerated silicon group appears also on the fracture surface. © Published under licence by IOP Publishing Ltd.

The long-term use of calcium hydroxide and the recent increase in the use of hydraulic calcium-silicate cements as direct pulp-capping materials provide important clues in terms of how reparative dentin may be induced to form a "biological seal" to protect the underlying pulp tissues. In this review article, we discuss clinical and molecular perspectives of reparative dentin formation based on evidence learned from the use of these pulp-capping materials. We also discuss the emerging role of calcium as an odontoinductive component in these pulp-capping materials.

Thermal resistance and temperature distribution for high-power AlGaInN LED chip-on-board arrays in blue and white versions were measured by different methods and tools. The p-n junction temperature was determined through measuring a temperature-dependent forward voltage drop on the p-n junction, at a low measuring current after applying a high heating current. Furthermore, the infrared thermal imaging technique was employed to obtain the temperature map for the test object. A steady-state 3D computational model of the experimental setup was created including temperature-dependent power dissipation in the LED chips and partitioned interfacial thermal resistance between the heatsink and the LED array. Simulations of the heat transfer in the LED array were performed to further investigate temperature gradients observed in the measurements.

Plasma electrolytic oxidation (PEO) is a common means for the surface modification of light metals. However, PEO of magnesium substrates in dilute electrolytes generally leads to the formation of coatings consisting of unfavorable MgO magnesium oxide. By incorporation of electrolyte components, the phase constitution of the oxide coatings can be modified. Coatings consisting exclusively of MgAl2O4 magnesium-aluminum spinel are produced by PEO in an electrolyte containing hydroxide, aluminate, and phosphate anions. The hardness of the coatings is 3.5 GPa on Martens scale on average. Compared to the bare substrate, the coatings reduce the corrosion current density in dilute sodium chloride solution by approx. one order of magnitude and slightly shift the corrosion potential toward more noble values.

A FRP-aluminium composite curtain wall panel, consisting of exterior aluminium plate, fibre reinforced polymer (FRP) laminates, foam core and interior gypsum board, was proposed by a research group in the Hong Kong University of Science and Technology to achieve high strength and stiffness, efficient energy saving, good fire resistance as well as great sustainability for modern curtain wall systems. To optimize the thermal performance of the panel and reduce energy consumption to the greatest extent, a phase change material (PCM) layer was also considered by the researchers. In this study, a series of large-scale structural experiments were conducted to experimentally investigate the flexural properties of the panel under a uniformly distributed load. Two typical loading directions, windward loading, with the exterior aluminium cladding taking a uniformly distributed load, and leeward loading, with the interior gypsum board taking a uniformly distributed load were adopted to investigate the effect of loading direction on the flexural properties of the panel. Three groups of specimens with different core thickness and composition were tested under the above loading cases to investigate the influence of the core thickness as well as the PCM layer on the flexural properties of the composite curtain wall panels. From the results of large-scale testing, it was found that with a good combination of different layers of materials, the composite panels achieved excellent flexural performance for the two loading conditions. What is more, it can be seen from the test results that as the cross section of the panel was asymmetric, the panel had different flexural properties under serviceability condition and flexural properties beyond serviceability condition under different loading directions, and the loading direction had different impacts on the flexural properties of the panels with and without the PCM layer. The test results also show that, for both loading directions, with

A FRP-aluminium composite curtain wall panel, consisting of exterior aluminium plate, fibre reinforced polymer (FRP) laminates, foam core and interior gypsum board, was proposed by a research group in the Hong Kong University of Science and Technology to achieve high strength and stiffness, efficient energy saving, good fire resistance as well as great sustainability for modern curtain wall systems. To optimize the thermal performance of the panel and reduce energy consumption to the greatest extent, a phase change material (PCM) layer was also considered by the researchers. In this study, a series of large-scale structural experiments were conducted to experimentally investigate the flexural properties of the panel under a uniformly distributed load. Two typical loading directions, windward loading, with the exterior aluminium cladding taking a uniformly distributed load, and leeward loading, with the interior gypsum board taking a uniformly distributed load were adopted to investigate the effect of loading direction on the flexural properties of the panel. Three groups of specimens with different core thickness and composition were tested under the above loading cases to investigate the influence of the core thickness as well as the PCM layer on the flexural properties of the composite curtain wall panels. From the results of large-scale testing, it was found that with a good combination of different layers of materials, the composite panels achieved excellent flexural performance for the two loading conditions. What is more, it can be seen from the test results that as the cross section of the panel was asymmetric, the panel had different flexural properties under serviceability condition and flexural properties beyond serviceability condition under different loading directions, and the loading direction had different impacts on the flexural properties of the panels with and without the PCM layer. The test results also show that, for both loading directions, with

A FRP-aluminium composite curtain wall panel, consisting of exterior aluminium plate, fibre reinforced polymer (FRP) laminates, foam core and interior gypsum board, was proposed by a research group in the Hong Kong University of Science and Technology to achieve high strength and stiffness, efficient energy saving, good fire resistance as well as great sustainability for modern curtain wall systems. To optimize the thermal performance of the panel and reduce energy consumption to the greatest extent, a phase change material (PCM) layer was also considered by the researchers. In this study, a series of large-scale structural experiments were conducted to experimentally investigate the flexural properties of the panel under a uniformly distributed load. Two typical loading directions, windward loading, with the exterior aluminium cladding taking a uniformly distributed load, and leeward loading, with the interior gypsum board taking a uniformly distributed load were adopted to investigate the effect of loading direction on the flexural properties of the panel. Three groups of specimens with different core thickness and composition were tested under the above loading cases to investigate the influence of the core thickness as well as the PCM layer on the flexural properties of the composite curtain wall panels. From the results of large-scale testing, it was found that with a good combination of different layers of materials, the composite panels achieved excellent flexural performance for the two loading conditions. What is more, it can be seen from the test results that as the cross section of the panel was asymmetric, the panel had different flexural properties under serviceability condition and flexural properties beyond serviceability condition under different loading directions, and the loading direction had different impacts on the flexural properties of the panels with and without the PCM layer. The test results also show that, for both loading directions, with

This work reports two large-pore stabilized MIL-53(Al) metal-organic frameworks prepared via solvothermal synthesis strategies that possess no or only slight breathing behaviour. Powder X-ray diffraction confirmed one material remains in the large-pore form under all conditions, while the other material undergoes a more gradual breathing transition than is observed for MIL-53(Al) prepared by traditional methods. Solid-state NMR was employed to elucidate additional structural information and gain insight into the role synthesis solvent plays on breathing behaviour. The CO2 and water adsorption of these large-pore stabilized materials were studied, and the improvement in CO2 loadings over MIL-53(Al) prepared by traditional methods was discussed., Published in the Journal of Materials Chemistry A, 2014.

A number of iron(II) complexes have been synthesized on the basis of benzothiazolylformazans, and their structure and composition have been characterized by elemental analysis, mass spectrometry, and X-ray analysis. The catalytic behavior of Fe(II) formazanates in the reaction of ethylene oligomerization in the presence of various organoaluminum compounds has been studied. Methylaluminoxane facilitates the formation of α-olefins (butene-1, hexene-1) and the byproducts hexene isomers; ethylaluminum dichloride (AlC2H5Cl2) increases the selectivity for alkyltoluenes. © 2013 Pleiades Publishing, Ltd., This work was supported in part by the Russian Academy of Sciences under Presidium program no. 3 “Energy aspects of deep processing of fossil and, renewable carbonaceous resources” and the Russian Foundation for Basic Research, project no. 11 03 90724 mob_st.

Magnesium aluminum silicate (MAS), a negatively charged clay, and nicotine (NCT), a basic drug, can interact electrostatically to form microparticles. Chitosan (CS) was used for the surface modification of the microparticles, and a lyophilization method was used to preserve the original particle morphology. The microparticles were characterized in terms of their physicochemical properties, NCT content, mucoadhesive properties, and release and permeation across porcine esophageal mucosa. The results showed that the microparticles formed via electrostatic interaction between MAS and protonated NCT had an irregular shape and that their NCT content increased with increasing NCT ratios in the microparticle preparation solution. High molecular weight CS (800 kDa) adsorbed to the microparticle surface and induced a positive surface charge. CS molecules intercalated into the MAS silicate layers and decreased the crystallinity of the microparticles, leading to an increase in the release rate and diffusion coefficient of NCT from the microparticles. Moreover, the microparticle surface modified with CS was found to have higher NCT permeation fluxes and mucoadhesive properties, which indicated the significant role of CS for NCT mucosal delivery. However, the enhancement of NCT permeation and of mucoadhesive properties depended on the molecular weight and concentration of CS. These findings suggest that NCT-MAS microparticle surface modified with CS represents a promising mucosal delivery system for NCT.

Magnesium aluminum silicate (MAS), a negatively charged clay, and nicotine (NCT), a basic drug, can interact electrostatically to form microparticles. Chitosan (CS) was used for the surface modification of the microparticles, and a lyophilization method was used to preserve the original particle morphology. The microparticles were characterized in terms of their physicochemical properties, NCT content, mucoadhesive properties, and release and permeation across porcine esophageal mucosa. The results showed that the microparticles formed via electrostatic interaction between MAS and protonated NCT had an irregular shape and that their NCT content increased with increasing NCT ratios in the microparticle preparation solution. High molecular weight CS (800 kDa) adsorbed to the microparticle surface and induced a positive surface charge. CS molecules intercalated into the MAS silicate layers and decreased the crystallinity of the microparticles, leading to an increase in the release rate and diffusion coefficient of NCT from the microparticles. Moreover, the microparticle surface modified with CS was found to have higher NCT permeation fluxes and mucoadhesive properties, which indicated the significant role of CS for NCT mucosal delivery. However, the enhancement of NCT permeation and of mucoadhesive properties depended on the molecular weight and concentration of CS. These findings suggest that NCT-MAS microparticle surface modified with CS represents a promising mucosal delivery system for NCT.

The objective of this work is to evaluate the reaction initiation characteristics of quasi-statically compressed intermetallic-forming aluminum-based reactive materials upon impact initiation, consisting of equi-volumetric tantalum-aluminum, tungsten-aluminum nickel-aluminum, and pure aluminum. A modified Taylor rod-on-anvil setup was employed to determine the reaction initiation threshold kinetic energy and actual energy for plastic deformation and subsequent reaction. Experimental sample remnants were recovered and examined through X-ray diffraction to determine reaction products., The original document contains color images.

In this project we introduced a new approach to obtain nanostructured organic-inorganic ceramic materials using the sol-gel method combined with high-pressure technique to produce ceramics with multifunctional properties. We investigated hybrid nanostructured materials, exploring alumina, zirconia and silica systems using carbon nanotubes (CNTs) as nanofibers reinforcements. The main challenge in CNTs- reinforced ceramic nanocomposites is the uniform dispersion of CNTs into the ceramic matrix and to obtaining a good interface between the CNTs and the matrix. This step is fundamental and we were able to achieve that. It was produced powders of nanocomposite materials of CNT/ alumina and CNT/zirconia. This materials and its applications are the subject of two PhD Thesis, that should be finished by the middle of 2012. several works were already published on this matter and some were presented in International Meetings., The original document contains color images.

Aluminum cluster-containing materials offer several potentially important advantages over current aluminum particle-based propulsion technologies. Both theory and experiments suggest that the preparation of such materials may be feasible. During our recent AFOSR grant, by utilizing anion photoelectron spectroscopic techniques, we have investigated salts composed of alkali cations and multiply-charged aluminum cluster anions, magnesium-aluminum clusters, gold-aluminum clusters, aluminum monovalency in Al7-, aluminum hydride polymer anions, hydrogen atom selectivity in Al13H-, magic numbers in aluminum hydride anions, and gallium nitride clusters. Nine publications and two PhD theses have also resulted from this work., The original document contains color images.

The influence of nanoscale reinforcement on the mechanical behavior of ultrafine-grained composites was studied. Al 5083 (Al-4.5 Mg-0.57Mn-0.25Fe) composites, with grain size of 115 nm and B4C reinforcement size of 38 nm, were fabricated via cryomilling and consolidation. The result reveals that the presence of nanoparticles enhances strength by interacting with dislocations, while simultaneously retarding grain growth. Furthermore, the nanoparticles-reinforced composite exhibits enhanced plasticity relative to the same material reinforced with micrometric particles. The underlying mechanisms are discussed., Published in Scripta Materialia v65 p652-655; published online 1 Jul 2011. Prepared in collaboration with Department of Chemical Engineering and Materials Science, University of California, Davis, CA. Government or Federal Purpose Rights License. The original document contains color images.

The response of the local structure of various types of spinel aluminates, ZnAl2O4 (normal spinel), MgAl2O4 (partly inverse spinel), and Li0.5Al2.5O4 (fully inverse spinel), to mechanical action through high-energy milling is investigated by means of 27Al MAS NMR. Due to the ability of this nuclear spectroscopic technique to probe the local environment of Al nuclei, valuable quantitative insight into the mechanically induced changes in the spinel structure, such as the local cation disorder and the deformation of the polyhedron geometry, is obtained. It is revealed that, independent of the ionic configuration in the initial oxides, the mechanical action tends to randomize cations over the two non-equivalent cation sublattices provided by the spinel structure. The response of the spinels to mechanical treatment is found to be accompanied by the formation of a non-uniform core-shell nanostructure consisting of an ordered crystallite surrounded by a structurally disordered interface/surface shell region. Based on the comparative NMR studies of the non-treated and mechanically treated spinels, an attempt is made to separate the surface effects from the bulk effects in spinel nanoparticles. The non-equilibrium cation distribution and the deformed polyhedra are found to be confined to the near-surface layers of spinel nanoparticles with the thickness extending up to about 0.7 nm. The cation inversion parameter of the mechanically treated spinel is compared with that of the non-treated material at non-ambient conditions. © 2011 The Royal Society of Chemistry.

Hole transitions from the heavy-hole hh to the light-hole lh band contributing to the 4-10 microns response range are reported on p-GaAs/AlGaAs detectors. The detectors show a spectral response up to 16.5 microns, operating up to a temperature of 330 K where the lh-hh response is superimposed on the free-carrier response. Two characteristic peaks observed between 5-7 microns are in good agreement with corresponding energy separations of the lh and hh bands and thus originated from lh-hh transitions. Results will be useful for designing multi-spectral detection which could be realized on a single p-GaAs structure., Published in Applied Physics Letters, v97 article 091104, 2010.